1. Field of the Invention
This invention relates to automotive wheel alignment testing equipment for use in aligning wheels of an automotive vehicle. In particular, this invention relates to a system having electrically-operated gauges which measure angles of caster, camber, turning radius, and toe-in or toe-out of the wheels of a vehicle.
2. Description of the Prior Art
An early patent was issued to Miller U.S. Pat. No. 2,020,614 which describes a wheel alignment system that is mounted on an elevated rack on which swivelled blocks with upstanding walls for receiving the wheels are mounted. These blocks are movable and spring-actuated toward the opposite wall. This apparatus serves to ascertain the alignment of the wheels of the vehicle and camber of each wheel.
The Love U.S. Pat. No. 2,676,415 describes wheel alignment equipment for detecting and indicating the misalignment and the camber of wheels of a vehicle. This equipment is readily portable and it includes a turntable or platform that has sides that will contact the rim of each wheel. The platform moves in response to a side thrust that is exerted by a misaligned wheel through the lowermost point on its rim when the wheel is driven on the top surface of the platform. The amount of shift of the plate or platform is usually indicated on a scale by a pointer that is operatively-connected to the platform.
The Smith U.S. Pat. No. 2,045,108 describes a turning alignment gauge comprising a pair of wheel-supporting elements, and means for indicating the amount of rotational movement of the table with respect to a movable indicator. The table supports substantially parallel rollers which engage the opposite sides of the tire.
The Haucke U.S. Pat. No. 2,167,361 describes a wheel alignment apparatus by means of which all the various alignments of the wheel and the chassis may be checked simultaneously. This apparatus comprises a beam that is rotatably-mounted on the base plate, and a pair of rotatably-mounted cradles are slideably-mounted on the beam. The cradles include means for centering the wheels therein. Means are provided for indicating the amount and direction of rotation of the cradles caused by the insertion of the wheels, as well as means for simultaneously indicating the amount and direction of rotation of the beam.
The Jordan U.S. Pat. No. 3,758,958 describes a wheel-aligning apparatus for selectively measuring camber, caster, and toe conditions, which apparatus includes means adapted to be connected to the side of a wheel, and a measuring circuit including a sensor mounted on said means and including means variably passing current in accordance with the position of the sensor. This Jordan invention provides an electrical circuit including a single sensing device and a single measuring instrument, together with an associated mechanical linkage for measuring the three angles of wheel alignment.
The Dick U.S. Pat. No. 4,110,913 shows an automobile front end alignment equipment comprising a pair of wheel-mounted trucks which are joined together by a parallel bar and are free for universal movement on a horizontal surface, and which support respective carriages for free-swinging about respective axes. These carriages engagingly support the front wheels of a vehicle in a predetermined relation. A bracket is attachable to a wheel whereby correlated toe-in, toe-out, and camber of the wheels may be simultaneously measured. A galvanometer indicates the degree of camber of the wheel.
The Mineck U.S. Pat. No. 2,953,857 describes a wheel alignment testing machine that requires complex machinery for engaging the wheels. This patent utilizes a magnetically-held disk which is applicable, first to a basic test bar and then to the outer face of the wheel hub for checking wheel alignment requiring only the removal of the wheel disk and grease cap of the front wheel hub.
The Darton U.S. Pat. No. 2,261,342 describes wheel alignment equipment built into the floor of a test bay. A pair of plates support the front wheels of a vehicle. These plates are in turn supported on cars which travel on rails or tracks. Rack and pinion mechanisms serve to move the plates, and there are indicating means for measuring the extent of movement of the plates.
The Musselman U.S. Pat. No. 1,950,994 describes a wheel alignment testing machine having a large platform with spaced openings therein, and wheel-supporting plates supported therein for lateral floating movement. These wheel plates are provided with supporting rollers. Each plate has a rack bar which projects into a central housing. Mounted within this housing is a rheostat device comprising a pivoted resistance element carrying member.
The Casler et al. U.S. Pat. No. 1,808,287 describes a wheel alignment gauge comprising a movable platform for supporting the vehicle wheel, an indicator which indicates misalignment of the wheel, and an auxiliary movable member or platform in advance of the platform that is adapted to eliminate tire distortion built up in approaching the device, so that the indicator will indicate the true degree of said misalignment when the platform is traversed by the wheel.
The Jarman et al. U.S. Pat. No. 4,167,816 describes a radius turntable gauge for front end alignment of motor vehicles. There is a supporting frame on which the turntable assembly is suspended by cables. A rod joins the two supporting frames.
The second Dick U.S. Pat. No. 3,457,653 describes wheel alignment equipment having electrically-operated gauges which indicate the camber of the wheels and the degree of toe-in or toe-out of the wheels. There is an upright column that can be attached to a wheel, and an indicator arm is pivotally-connected to the column and it can be adjustably swung to a horizontal position. The swinging of the adjustment arm actuates a potentiometer to cause registry on a galvanometer of a value determined by the degree of camber of the wheel.